Looks like a Pommy cousin of the Crown and Birko 40L boilers here in Australia. I have 2 of those and they do a cracking 23L length of beers using BIAB, can handle 5 - 6% ABV no problems. I don't know how robust the tap is but I'd try it out with the native tap first, I haven't bothered replacing my taps with ball valves and they work fine.
Edit: When I lived in Cardiff I had a 5 gal. Bruheat for several years and it worked reasonably well, but the problem was that you had to stir constantly during mashing due to hot spots, and after sparging into a second couple of smaller vessels then cleaning the bruheat out, pouring the runnings back in and boiling - and as pointed out it was easy to get a boilover - at the end of the day you could only get one four gallon pressure barrel out of it. Far better to get the bigger size of boiler.