Bad credit - better chance with my own bank/BS?

caroline1973lefty

I’m hoping to get a mortgage (am 1st time buyer) in a year or so as have been offered some family help. I might be able to get a 10% deposit together, maybe 15% at a stretch.
for ages I’ve thought I’d never be in this position, so any advice people can offer would be really appreciated. 

I’ve got a 2.5 year old default showing on my credit record (for 1k), otherwise my credit record is good. I’m actually thinking about challenging the default (for various reasons that seem good to me!) but I know that’s a long shot even so.
Do I have a better chance of getting a mortgage (even, one at a half decent rate) with a bank I already bank with?
I’ve banked with Natwest for decades (and recently also opened a help to buy isa with them). Would they take any of this into account? I also recently opened a First Direct account (mostly for the cash back to be honest).
Is it worth opening a new account with a bank or building society now in the hope they might then be more open to giving me a mortgage in say a year’s time? Are there any particular banks or building societies worth considering particularly for this purpose? I read that building societies may be more flexible - any in particular? I’m in the SW/Midlands, I know some building societies seem to have savings (and maybe mortgage?) offerings for people in particular areas (Monmouthshire and Newbury are 2 I came across in my area, for example).  

MovingForwards

You are best off with a mortgage broker who will find the right lender for you, your deposit, your long-term plans.

ACG

Natwest prefer defaults/CCJs to be satisfied. 
10% gifted deposit and an unsatisfied £1k default is not a great mix. Thats not to say you wont be accepted, but its not a great idea to choose a lender based on who you bank with. You need to understand their appetite for your circumstances.