TP Link recommendation

Range is line of site Point to Point (from one nanostation to another). If you can get a 2.4GHz nanostation mounted on an outside wall facing the garage you might get enough signal inside to work. If that doesn't work then put up another nanostation on the wall outside the garage to complete the bridge. If you have a window in the house facing a window in the garage you might get away with a nanostation (or similar) inside the window behind the glass - bewear glass with a metallic coating it blocks the signal.

You do need line of site but 2.4GHz is better with obstructions than 5GHz.

Running a cable is not that hard across grass you can just make a notch with a spade and push it down a few inches - thats how one electician I know does cat 5 cable - but use external cable it has an extra tuffer external layer. That said I've hand standard cable outside in the open and buried for 10 years and its still find.

Hmmm awkward, just because you are going to have to run cables one way or another even if you use a wireless link.

Ideally you run cables to the walls outside facing each other either side of the car.

Is there anywhere internally you have cabling like cat5 (6)?

The garage side shouldn't be too bad. Cable up into the roof across and down the sofit to the wall.

In the house I'd investigate following the cable for the satellite to get from Point 1. Then if all else failed I'd go out through the wall at the side of the house at Point 1 straight up the wall into the roof through the soffit across the roof and out again on the soffit on the side facing the garage.

Another possible is to come out at Point one and put a post in the hedge in the garden and put one side of the link there. Do the same at Point 2 and put a post to mount the outer part of the link somewhere in the hedge between Point 2 and the outside light nearest the garage. Obviously you want the nanostations to be far enough into the garden so they face each other. Mounting at 4 ft off the ground is fine. Ideally mount both at the same height facing each other but for the distances involved you really won't need to.

Edit> Sorry yes two and a good bit of cable by the looks of it. One on the wall of the house facing the garage might just do it but will be better with 2 and the garage is the easier bit of it.

If you want to keep both (garage and garden office) then you only need the one base station on the house. When you set up these point to point links one is set as the base sand the others as stations (in the nanostation terminology).

With the brick garage I think you might have some luck with just a base on the house wall facing the garage. You have to make a change in the firmware so a laptop will pick up the signal directly but its close enough to work. I'd be less hopeful about getting a signal through the walls of a steel shed so there you are going to need the two.

Did you try powerline adapters - worth a shot? Buy them on Amazon and send them back if they don't work?

Now back to cable. Don't look at the straight path between the house and garage. Remember with Cat5,6 etc you can have up to 100M of cable and more with inline PoE adapters. So is it 100m from Point 1 through the wall over to the boundary along the boundary into the back garden along that boundary and then back down to the garage and in at Point 2? If you can be careful hedge cutting then you can just run a cable through the middle of a hedge and tack it to any wooden fencing. Where it has to go over an area of concrete like a path at the left hand side looking at the house then just get a rubber mat with a cable channel in it. Same route could go out to you new garden office.

Edit>....

With cable I wouldn't get to hung up on type of cable or doing a perfect job. A box of good cable (some is rubbish avoid any that says its CCA) will set you back about €120 for 305 meters. Then another €20 for a cheap termination tool and a few RJ45 plugs (Amazon prices). So if you happen to damage the cable you have a minimum of 2 replacements if you buy a full box. Making your own terminations means you only need to drill a hole in the wall the size of the cable and not wide enough to get an RJ45 through.

Sorry if I've made it more complicated. As I keep saying you might find one nanostation on the wall will do all that you need.

If you are getting electricity out to the garden office can you run a cable at the same time?

You might even get away with a mesh, provided you can get one device near the house wall near the garage and another near the garage wall near the house. Won't be perfect but perhaps good enough for work?

So here's something you could try. Disconnect your current internet providers router and take it into the room at the front that has the wall facing the garage. Plug it in to the mains but don't worry about the internet connection. Now see if you can pick up the signal from the routers WiFi out in the garage. If you can get 50% or more of signal strength you'll know all you need is a "booster box" of some kind in that room. You can try the router in different location and see if one is best for getting a signal out in the garage (include upstairs).

Thats the sort of thing. In hope more than expectation I'd go up to the AV1000's. You need to try them for a couple of days to see how they go. Often they will either not work at all or start at a really fast speed and then slow down as they encounter more noise on the mains supply. However I have had them working perfectly in a couple of location. As the power circuit in the house will be different from that in the garage then may not work but as I said if you don't try you won't know.