Is £50K enough for a loft conversion - London

[newlabelwriter]

Just that really. We'd be looking for something quite standard. We're in a Victorian terrace and looking to extend to get one more bedroom and another bathroom. Also any recommendations in South London. TIA

Almost certainly no.
Number of factors including state and orientation of your joists, structural requirements. Architects, structural calcs and planning fees will be around 10k before you ever start

We did a loft extension in south London 4 years ago at £36000 quoted basic costs for a 1930s house - master bedroom, study and shower room. Add to this more sockets and lighting, plus decorating, bathroom and carpets it was probably about £10k more than that. I think you be should be ok with your budget but it will depend on the size of the loft, your willingness to do some decorating yourself and your choice of flooring and bathroom fittings. Also you need to budget for about £2k surveyor costs in case your neighbours want to appoint a surveyor for the party wall.

Will you need a dormer? That pushes the cost up.

You shouldn’t need planning permission unless it’s huge or you are in a conservation area.