@Jamie *****
obviously .the main page of your passport and your personal details. You must also have your flights booked and send them a copy of your e ticket. They want details of where you'll be staying. I have my own apartment and earlier this year they really wanted the details. This time not so much. They want 3 months of your bank statement showing an income going in whether it be your pension or salary and the amount is not too high. The rest is a passport type photo pretty recent as it is put on the e Visa you get. The application form is pretty straight forward. And you can save it and go back to it until you're complete. Then you pay using your bank card £150. They might come back to you if they want more information all done by email but this time mine went through quickly and I received it next day but it took me 3 weeks to do in January hence my early application this time. They are mainly interested in making sure you have enough income to support yourself and have a place to stay. No insurance was required which is a blessing for me as I'm 80 with cancer and basically uninsurable. It's really quite easy. I hope this helps.