The 2nd reptile forums link you posted are ones ive had my eye on already got some pics of them, others in Bournemouth are abit to fsr awag unfortunately.
The best place is the store I sent you as they also deliver animals to your door and they have CB17 ATBs which are perfect for you to learn with as they grow.
I noticed you were on the reptile forum and had a Boa with a RI problem, did you get that resolved before you got rid of it,when you had the landlord problem?
Also after you get the ATB stick to 3 snakes only as anymore will start becoming a husbandry problem if they become ill. That's why I was saying get something you really want to keep as a pet to its full life, don't use them as trading cards because they do become attached to their owners, some will disagree here but that just shows to me they don't spend enough time with them.
I also read you were worried about bites from the Boa at one and a half feet size, I hope you have got over the snake bite issues as that's all part of keeping snakes they do bite from time to time and some will always bite and known for it. ATBs,ETBs,GTPs,White lipped pythons, even Carpet pythons have a very painful bite (Morelia family, same as a GTP
https://en.wikipedia.org/wiki/Morelia_(snake), all these have painful bites) etc are very well known to be biting animals and the rare ones that don't but this is not the norm.
You stated also your Gopher snake is going threw a biting phase are you managing alright with that? Also is the Gopher snake behaving normally apart from that? Is it eatting, urinating and defacating as normal and shedding ok?
Snakes can become mean overnight when something is wrong or it's their time of the year sometimes. How old is the Gopher snake?
Also a heads up BRBs are also known to be bitey but they get used to their owners over time, one of the many reasons why they don't make a good starter snake.
If you have any problems do shout I will always help you with a snake issue,I have been threw it all and had to deal with it all from people that didn't take care of their snakes correctly, this is why I use to re-home them in past a lot as they get suddenly bitey and their owners are shocked and want rid of them and I get them and realise they are ill or not kept at the right conditions, then after curing the problems they become great pets again and some I even returned to their original owners after explaining the issues that caused the sudden changes they observed.
Remember ATBs are display snakes that can be handled from time to time (on a snake hook preferably, so to keep some distance between you and the snake, if it remains a nervous snake as most will), it's not a ball python or Boa, same applies to a GTP and ETB but the result with the last two is more serious to you as in painful bites and a lot stronger and faster snake. Reason I said ATB to you is because I see you have your heart set on a GTP or ETB and I wanted you to get use to the attitude of a snake with the same attitude as a GTP and ETB but easier to deal with first as a trial run to a GTP and ETB and ATBs are gorgeous snakes too that I know you will fall for big time once you keep it and may even start collecting the different phases they come in before you even consider a GTP or ETB.
, but not one of them yet but a nice "arboreal" species that can behave as badly as they can but at a cheaper price and look very pretty in a display and a snake on my next display setup as I really like one of the morphs they come in 
. Also their bite is no where near as bad as a GTP or ETB.
