For OA just apply online for basic CRB check ( about £23) just shows last 5 years and is accepted for OA visa. Make sure you apply direct to DBS, not use an agency, which takes longer and is more expensive
Revolut, Monzo, Starling. No foreign exchange fees. All online. Report your old card as lost, get it blocked and new one issued. Remember in Thailand most ATM's issue cash first, then return card.
should still have time, provided first flight isn't delayed. Ask for you bag to be tagged rapid transit, at Bremen. So it's loaded last and comes off first.