If you go to your avatar in the top right, you can get to a menu option for Account Details. In there, you can add your location and grow zone. Nearest metro is good enough. Then that information will be to the left of every post. It's really helpful to have that information when giving advice and then people won't have to ask all the time
Typically consumer level bonsai "kits" are packed with common bonsai varieties...typically things like maples, elms, wisteria, and Japanese black pine...maybe a few others. I would not expect birch and currant to be in that mix...but who knows??
Did the kit come with the pots? With any other tools, soil, etc? I did a quick search of Amazon.uk for kits that might come with coconut coir pots like in your picture. The only one I found easily was this one:
Great prices on your favourite Gardening brands, and free delivery on eligible orders.
www.amazon.co.uk
which doesn't sound like what you have. You might try a quick amazon search to see if you can find your kit...there may be more information there.
If that doesn't work, do you have any seed remaining? A picture of the seed would help narrow down the options considerably! Or, if you could describe the seed/recognize a picture of it, that might help. For example, the 3rd picture may very well be an elm. Was the seed shaped roughly like these:
You can try googling for images of the other species people have suggested to see if the seeds match your memory...that might help. Seed morphology is a primary indicator for many, many species...often better than leaf morphology