Self Employed - What Do I Need To Do To Get A Mortgage?

I was wondering if anyone could give me their insight in what I need to do and where I need to get to in order to get a mortgage. I am self employed and have been for a number of years.

This is some info:
2015/2016 -Gross was 23k, Net was 14k
2016/2017 - Gross was 25k Net was 0. This was 0 net because I chose to put all my profits back into the business in order to increase income.
2017/2018 - By April should be around 65k Gross, 38k net
For 2017/2018 tax year which is nearing its end. Until Oct I was putting all money back into business and now will start finally taking a proper wage from February onwards (January was my first drawings from it of 1000). I intend to give myself 4k a month.

I am currently a sole trader but will be changing this to ltd for next year as the expected profits will be at least double what they were this year based on projections (around 80k profit) and what I have made in the last few momths including how january is going. I still intend to pay myself 4k a month though for the minute to keep my income consistent, even though there is potential to have a larger income.

My income is such that I get paid in arrears - so I make money for a company then they pay me 2 months later for that. As a result I can see what I am getting paid 2 months before I get paid. My account shows over 30k income to be paid in the coming months. I thought I would add this here in case this could be handy information.

Anyway ideally I would like a mortgage between 250k-300k. 300k would be better but I would settle for 250k. (I am under no illusions that I can afford that right now or that I can expect a mortgage right now). Where I live anything less would be a cluster home and I have lived in one of those before and could not do it again.

I could have the option of moving to a cheaper area as my work doesn't require to me at a fixed location but there are reasons I want to stay here. I have an open mind though.

I was wondering what sort of deposit I would need and how long until my accounts would be accepted as decent income to be considered for any type of mortgage. I know it is difficult to get one self employed so I am under no illusions that I will be given one tomorrow. I would be a first time buyer too so do not have any experience with the process, but wanted to get a general idea of what I need in order to be in a position to be offered a mortgage.

Thanks for the help and reality check.