My dad is a farmer and I'm fortunate enough to have a free plot with one of the outbuildings.

Again, being a farmer we can save quite a bit with doing a self build project, in the sense we have access to excavators, trailers, soil, aggregate, etc.

Anyway, my parents recently did something similar last year and put up a pretty decent standard house for about £120k - without valuation I would imagine this house to be worth in the region of £225-£250k - that is just based on similar houses in the area (West of Scotland). I'd be looking to do the same. However my parents paid for this with savings, thus have no mortgage.

I am looking to do the same, however my stumbling block is both myself and my partner have a mortgage on a flat each (She has paid about £40,000 off of a £105,000 mortgage, I have paid about £4000 off a £32,000 mortgage). I also have a buy to let property (£28,000 interest only mortgage).

We are reluctant to sell any of these as her flat, and my buy to let both provide decent rental income. My current flat will also provide rental income if it was to go on the market.

My question is, how will this affect us if we go to get a self build mortgage.

I am self employed with an average income of around £45,000 my partner is PAYE with an income of £28,000