You can enter visa free for 30 days, however you need proof of onward travel within the 30 day period. You had better buy a flight to another visa exempt country nearby like Malaysia RIGHT NOW. You may not be allowed to board your flight to Thailand without it.
You don't need a visa (I don't think for NZ) to fly to Malaysia. Go for a couple days, re-enter, then extend before the new 30 days expire. (Or go there for a week and apply for a Thailand long term visa.) You cannot get a visa to cover your stay now... too close to your flight. And you can't get it in Thailand.
I have flown Thai Airways LHR to HKT 3 times since October. Very good price for a mainline airline. The service is good. Seatback movies, food was good for airplane food (has some heat of course, but not too much.) No issues. The captain apologized for being 5 minutes late on departure once.
, if you also plan to visit other countries, you can arrive to Thailand visa exempt for 30 days (ie, just bring your UK passport and proof of outward travel from Thailand). But you then either have to get a 30 day extension (also mentioned above) or depart Thailand before the 30th day (even for just a day), and then come back for another 30 day visa exempt.
Banks worldwide are moving customers (or trying to) away from coming to the branch. If it is something that can be done online, they will push you to that. The manpower time to do mundane work is a cost that banks worldwide are trying to reduce.
Anywhere along the BTS from Soi 2 to about 26 would suit the needs of a first time traveller. PLENTY of hotel choices, plenty of malls, plenty of food. But also plenty of local feel when you walk down the sois. And the BTS is close by for going out to explore.
Bangkok is an old city mixed with NEW. My favourite city!
I don't really sleep on planes, so I would be exhausted when I get to BKK. Then that means I'd be awake until my hotel room is available, and my body clock would be screwed for 3 or 4 days.