Not sure where to begin

Hi all,

I've recently inherited my family home, it is a bungalow in rural location, around 1 km outside a village in the west. I am happy with the location, however the house is too big for my needs (single, no family or plan to have family), the house through various extensions has now 4 and half bedrooms, it is structurally sound, but has always suffered from poor light and as bits were added on over the years, the heating has never been sufficient (its oil fuelled heating). Apart from being too big for my needs, being dark and costly to heat, it is also situated extremely close to a busy road, ie walk out the front door and a passing lorry is likely to shake you to the core, gravel also occassional bounces off the road and bounces off the front windows its that close.

The thing is it is on a large enough site behind it, plenty big to build a new house. My options as i see them are to do a big renovation job on teh house, including changing the orientation of house away from teh road, so it benefits from natural light and have living space away from road noise. i would also need to completely redo the heating system so it is functional and affordable. ideally i would just like to live in the original part of the bungalow as it has thick walls and is the warmest part, thinking i could block off the 2 bedroom extension which i really don't need and its hard to heat?

I only have a mortgage of 150k approved, I could possibly push for more but its probably all i can comfortably afford. The other option is to knock the original house and start from fresh in a better location away from the road up the garden, again i would be thinking of a small 2 bed bungalow, i know the price of building materials and labour maybe prohibitive for this. unfortunately i have absolutely no diy skills or family who work in the trades so can't get any of work done myself to save money it would have to be contractors all the way. Another option would be to build a timber frame modular home, one of the ones that actually meet planning permissions, which are actually around the 225k mark and probably as expensive as a new build.

So my question is who do i go to to decide which is most practical option, revamp current bungalow or try for a new build away from the road. Would hiring an architect or structural engineer be my first port of call, i would like to get a professional opinion as i don't want to pump money into the current house if its not practical… ie too big, hard to heat and it will always be too close to the road. on the other hand, i don't want to knock a livable in house, which coudl potentially be much improved with 150k cash injection.

any thoughts appreciated!