VJW,
In the UK Dan is correct. Who flies 737s -
Jet2 - fair enough but I believe their 737 recruitment is now pretty well complete.
Ryan Air - but you need no experience on type or type rating and be prepared to pay 35000 eoros for a rating that should cost about 20,000. And they fly NGs whereas bmi baby pilots will only have flown classics.
Thompson fly but they need to recall the furloughed pilots first.
Astreaus but you will end up based in Iceland or Bolivia or somewhere horrid.
Other than that just a few aircraft with air contractors, Titan etc.
But then an airbus rating is pretty useless unless you go to CTC and get a job with Easyjet. A Q400 rating is useless unless you get it with Flybe. Infact almost any type rating is useless unless you have plenty of hours on type or a job lined up when you do the TR. Or you are prepared to go abroad.
At the moment I would suggest that in the UK no type rating is very useful, including any of the five I have on my licence (all with PIC time on type and still unemployed in the UK).