Can I change my entry point to Thailand after applying for a visa in the UK?

ANY border but Aranyaprathet/Poipet, especially if you don't have your own car or motorcycle. There are 6 other Thailand-Cambodia border crossing points:

1. Ban Khao Din / Phnom Dey (this is the closest to Aranyaprathet/Poipet)

2. Ban Hat Lek (Khlong Yai) / Cham Yeam (Koh Kong)

3. Ban Pakkard / Psar Phrum

4. Ban Laem / Kamrieng

5. Chong Chom / O'Smach

6. Chong Sa-ngam / Choam

Choose one of those. Ban Khao Din is closest to Bangkok. Chong Sa-ngam is the closest border crossing from Siem Reap, but once you're across the border, the nearest larger city is Sri Saket. Ubon Ratchathani is the closest city with an airport. Cham Yeam is the closest border to Phnom Penh, but the highway (highway number 48) is still under construction and a bit rough in places. It should be mostly complete within 6-9 months from now.

You can enter from anywhere. Just be aware that the Cambodia (Poipet) border is notorious, there was a post the other day from someone who was not let in there on a DTV, you can find the whole story in this group

No, u will never be allowed into Thailand. They read every post, they listen to every conversation, they are literally inside your head... and they say "you shall not pass" as Cambodia border crossing is a cursed one. Only Bangkok will save you!

Enter anyway you like as long as you are in the UK when you applied and visa approved