Flying out to somewhere and seeing what happens is one of the best things I've ever done, I'd advise doing it but make sure you do have some knowledge of Thailand before you go, just to make things easier. Bangkok is pretty safe, and you should be okay there as a female. However, from what I saw in Bangkok, everybody mainly comes in groups and it would be difficult to make yourself apart of a group of people that already know each other.
I didn't see many lone travellers, but I guess if you look elsewhere you may find someone?
If you stick to the main cities or touristy parts of Thailand you will be more than fine on your own, if you're going to go a bit more rural I'd advise dressing modestly. But Thais outside the main tourists places are more friendly too. So yeah, if you end up on your own you should be okay unless you do something crazy.. Although, if you really want to travel with someone then there are websites like travbuddy which may help you find someone.
I went last summer with a mate to Thailand/Laos/Vietnam/Cambodia. Most people were in a pair or as part of a tour i found when i was out there...If you can't find a friend then sign up with one of the tours that STA recomended earlier. You'll be guaranteed an awesome trip with like minded people.
We flew out to bangkok with 0 plans other than attempting to get back to bangkok 9 weeks later. didn't even know where the city was from the airport when we landed or how to get there...
Basically i wouldn't reccomend travelling as a single female anywhere really. If you can get a friend to go with you then just go out there with no plans and blag it a little bit. Everything out there can be booked the same day for cheaper prices than you will get booking it from England. Go to this guy called "joe" just off Khao San road, behihng the temple, near my house guesthouse, he will sort you out all your travelling needs tbh. You can book it at the bus/train station yourself and save a dollar but by the time you spend $3 getting to the station and back and hours of your time, get other people to book it.
