The most important thing with bridging is knowing you can get off the bridge. So plan what the next step will be ie mortgage etc make sure you would have no problems moving to that.
Rule of thumb valuation was annuals rents as 5% yield. So yearly rent x20. With greater non deductibles, leasehold etc the property must still be worth north of £150k. I'd say closer to £200k.
I am going to review your older videos, but if you don't have one that explains what a bridging mortgage is and how to find those flats, could you create one? Do you find these properties at auctions? Additionally, could you keep us updated on your progress? I'm based in London and have recently decided to switch to buying BTL properties in Dubai, as I find the market there slightly better and it will help diversify my portfolio.