Rents are falling in London as people are moving out due to working from home. A 2 bed property would be easier to let out to a family or a couple/single person who want an office, and a 1 bed might be better for a working couple or single person who are/is unemployed or employed out of the house.
The government is hammering landlords for every penny they can get out of them. It's difficult to get non-paying tenants out so you'd be best to wait until you can find a tenant with an employed, home-owning guarantor who will sign a deed of guarantor. There is a lot more paperwork these days and you can be heavily penalised for non-compliance. If you let via an estate agent, YOU are still responsible for meeting any legal requirements, including securing the deposit in a scheme.
Calculate your yield - there are websites that'll do this for you. Work on 75% occupancy as a rough guide as this includes repairs.
If you intend to increase your portfolio it might be an idea to consider starting a ltd co, for tax reasons. Seek professional advice.
I'm a landlord and due to all the government's clobbering etc over the last few years, I've decided to invest elsewhere. Being a landlord is, considered by many landlords, to not be worth the stress. Most of the landlords I know are selling up as properties become empty. This does mean, however, that rents are going up. I let a property 18 months ago. The tenant has just moved out and the going rent is 20% more than I was asking 18 months ago. I'd like to charge the lower rent, but due to tax changes I will have to put the rent up to cover this.