Having two mortgages, renting out old house

[Jop19]

I've currently got my old house rented out (for £800p/m) after I moved out of the area. It's still on the same mortgage as it was when I bought it, which is an Interest only at £320 per month. Thing is I'm now looking to buy another house with my partner and wanting to work out whether to leave current place rented out or sell it - my equity is about 18% on it, and it's worth about £180k.

So....Question is, is it likely I'll be able to apply for another mortgage on top of my existing one, or are lenders likely to turn their noses up because they'll assume I'm overstretched? The rent on my house clearly more than covers the mortgage but I havent (irresponsibly perhaps) informed the mortgage lender for fear they'd try and switch me on to a less affordable b2l product.

For background, I earn circa 50k and my partner 27k. We're looking to buy somewhere up to 260k and have about 60k to put down. It's also apparent I could command another £50 per month on my rental place if needed. It let very easily within 24hrs, and in terms of return on my cash investment, I think is ok. But feel free to disagree, as I'm no property investor so yields and the like don't trip easily off my tongue...

Anyone learned in the field of finance and mortgages care to offer some opinions/advice/thoughts/insults?

[Jop19]

Sarnie said:

The new lender won't be interested in whether it's on a BTL product or not, just whether it's self-financing and whether it's likely to affect their risk in lending to you for the new property....
..

Thanks, sounds like I might have a shot at getting a mortgage then.

Im concerned about informing the lender as I've technically broken their rules and don't want to be triggered into switching to a BTL product. Maybe Roth steering clear of Barclays /woolwich

[Jop19]

I agree I've sailed close to the wind, and should have told the lender. Although it looks like they charge an additional 1% interest for consent to let.

[Jop19]

Yes. Insurers are aware. Consent to let will be sought as it does appear I've been somewhat laissez faire