Wildlife Photography and camaras

Go to London camera Exchange in Cheltenham and talk to them about your requirements and see what they have available the used section. That will give you a feel for some of the cameras that are going to be available within your budget range - don't forget that with a DSLR you are going to need a lens before you can use it for wildlife - ideally something 400mm or more - a 70-300mm zoom lens is really an absolute minimum but will still be quite limiting. A suitable lens is going to cost you more money so you need to research what you want in terms of a lens before you buy a camera otherwise you could end up with something that never gets used, if you cant afford a lens for it in future - personally I wouldn't rule out a decent bridge camera. London Camera Exchange will also have some used bridge cameras in stock that they can show you.
Remember that you don't have to buy from them and can try and find what you like on Amazon but it would be most useful to feel things out.
Good luck

Already suggested a shop visit Bob and already been told it ain't an option..I found a shop visit very useful and the guys were so helpful and knowledgeable regardless if you were buying or not

A budget of £300 is a considerable challenge to get DSLR & wildlife lens - in reality you're looking a fair bit more to get something that will work well for you (and you're really looking at 2nd hand). You could (in the Canon world) get a 7D2 just about for that, but a lens (whether Canon's Mk1 100-400 or a Tamron/Sigma 150-500/600) is probably between £500-£600 alone. More realistically, a 2nd hand 700D and 55-250 STM would just about fit the budget & is a nice little setup (I have exactly that sat in my kit cupboard for when I don't want to take out the heavy hardware), but the lens is a bit short for a lot of wildlife (birds in the garden are ok at that focal length, but out on a reserve it's less useful). At the price point we're talking about, high frame rates and full frame are probably off the table, though you could probably get a 5D2 and 70-300 just about (we're talking quite an old camera though)

Honestly, Zo, if you don't actually NEED the camera for the holiday, I would wait until you have time to go to a shop and actually hold some to get a feel for them. It's a lot of money to spend on something you may end up not liking, and therefore not using.

I need the camara for holiday. Mum says I need to decide by tomarow and I can’t leave it any later

Need or Want? Two different things. What's going to happen if you don't have the camera, except you won't be able to take nice photographs?

I know there two different things I don’t want it for holiday I need it for holiday so that I can test it out on holiday. I will be away most of july. But I’m not just choosing without thinking or choosing in a rush I’m trying to find the best Nikon or canon camara in that range for Wildlife photography. Mum won’t let me get one for 400 pounds cause she thinks it’s rediculous price for a camara and she thought 200 was bad enough. even though it’s my own money she still won’t let me get one for more than 300 pounds so it wouldn’t make any difference I told Mum I could put more money with that but she said no im to use it for other things

Cause it’s my own money it’s not up to Mum how much money I spend on the camara but Mum and Dad don’t know much about DSLR and mirrorless camaras but they won’t allow me to buy a camara up to 400 I could save more money but they still won’t order the camara unless it’s 300 pounds. I was going to save up to 300 then work towards 400 so 400 pounds was my original goal but unfortunately I can’t get one up to 400 even if I did cause I wouldn’t be allowed  regardless of holiday. 

I don’t know why she won’t let me get one up to 400 pounds but she is adamant so all I can do is get one in my budget range so anyones exspeariances in what I asked on the post would be helpful

Well, these two come in at £305 -
www.wexphotovideo.com/.../
www.wexphotovideo.com/.../
(other choices doubtless there but I haven't searched diligently - and remember you'll need an SD card too).
What are you aiming to be taking pictures of? That will help you decide if this is anywhere near suitable for your needs. It's not Amazon - you won't get stuff from Amazon 2nd hand I doubt - but WEX are reputable and you'll get a warranty on the kit. It's difficult if you're not in control of your own destiny (so to speak) so you have my sympathy!