Self-employed, house build, bridge loan & mortgage

Hello there.
Just a general enquiry for some guidance regarding my plans for next year.

I am building my house next year.
Cost to build 55k.
This will be built on an already owned plot of land.
I am self-employed. My income this year will be 15k-20k and the same will be for next year also, so i'll have 2 years showing a decent wage.
Savings will be 15k

I am looking for a 40k mortgage, seeing as the house is yet to be built I would assume that a bridge loan is needed for the 40k and then this turned into a mortgage set against the house when complete.

Please could you guide me as to what steps I can take to ensure I get the ball rolling and the money secured?

Thanks for your time.
Best regards,
Ruth.