Buy residential property and get a Self-Build Mortgage?

pmartin86

Afternoon All
I have a slightly odd situation and wondering if anyone can give me clarity on if what I'm thinking of is at all possible, I'll use approximate figures for illustration.

I've just agreed a sale on my house, this will leave me with Circa £120k cash, I'd like to build with a self build mortgage, breakdown of costs on a specific plot would be:

Land: £60,000
Build Price: £180,000-200,000
Est Final Value: £330,000-£350,000
I've got a standard DIP for for £295,000, so in theory could spend £395,000 on a "standard" house - How close would this be for a Self-Build mortgage?

In addition to the above, I also have the opportunity to buy a smaller house nearby for Circa £140,000, it requires cosmetic renovations that I would do myself, est £8,000-£10,000 - With an expected value for £160,000 when complete, basically about even once fees etc. are counted for - Would it be feasible to do the following:

Put 50k deposit to land and get self-build mortgage for the rest of the construction
AND
put 55k Deposit to £140k house and mortgage the remaining 85k, renovate while living there with income from wages and keep my 15k cash as a "build buffer"

This would essentially have me borrowing around the £295,000 mark total, wouldn't need to include the family business (Which isn't part of the DIP - Circa 30k profits per year) and would essentially save me 12-18 months of rent, which would be circa £800-£1200 a month in the area.

Any thoughts on my jumbles mess of thoughts appreciated, either just for the self build part or the whole thing.

Regards
Paul