Embarking on a similar refurb myself. New heating system, new boiler, total.rewire, new bathrooms (2), new downstairs loo. All wall replastered, new skirting boards, ceilings plastered, new light fittings installed, new sockets in each room, new gas pipes to a fireplace, patio doors installed, new kitchen installation, hiring of skip and removing everything.
£40k labour (hiring a builder and the electrician and plumbers/fitters all work for him).
But that doesn't include items, just labour. They will source most things for me, like rads, skirts, switches, etc. I will order all bathroom and kitchen units, patio doors.
£80k approx.
This also doesn't include floors and windows. The builders don't install those, so an extra £12k new windows, not sure on flooring costs yet. Also no decorative costs in there (lights, painting).
It's a 3 bed semi in east london/essex border. So, i'm guessing similar price.
Get a couple of builders round to quote if you can - we did before we bought it. Make sure your brother writes a list of what he wants done. The builder will advise of course. Then after builder gives a rough quote, if you're interested get him to cost against each item on the list as the next step.