Buy to let change of use from B1 commercial to residential

[revampneeded]

Hoping there are some UK property experts out there...

I'm looking at buying a small property that's currently office space (B1, which i think is now E(g)?). It's currently standing empty and in this area commercial tenants can't be had for love nor money + the market's likely to be saturated for the forseeable.

I want to convert it to residential, (presumably C3(a)?), but wondered if there's a use class that would allow the tenant to use it as combination home/workspace and gain a tax benefit accordingly?

Any thoughts very gratefully received.

Sui generis?

Hello, as this is quite specialist I recommend you post on landlordzone where there will be people who know about this area. Good luck.

Good suggestion, thank you very much!