When you don't see cards often, that's usually because they're kind of bad. Primarina might be okay once Aqua Patch is released but it will still generally be worse than things like Darkrai due grass weakness and 2nd stage mons being very vulnerable to item lock (since you need to search for more cards to come online and usually use rare candies to accelerate evolution).
Bewear is just a very lackluster card, it's not terrible but not great. Meganium is one of those cards that could be viable with a slightly more favorable energy requirement, but regardless it's a very difficult card to play around and not one I'd recommend for a new player. And without consistency cards like VS seekers and Shaymins, I doubly caution you to avoid trying to get too crazy trying lists with niche cards, these lists are already a lot less stable than more conventional decks and can become absolutely miserable to play without these core consistency cards.
I think that, currently, the best deck for new players in standard in terms of ease of use is Darkrai Turbo. Lurantis/Vileplume is also pretty easy to play, but without Shaymins it will have pretty bad consistency issues. I think the sweet spot between good, easy to play, and relatively budget right now is probably
Lapras's water box. Here's a budgetized example list
Pokemon - 11
Lapras-GX x3
Remoraid BKT x2
Octillery BKT x2
Manaphy-EX x1
Articuno AT x1
Glaceon-EX x2
Supporters - 12
Sycamore x4
N x2
Lysandre x4
Pokemon Ranger x2
Items - 21
Ultra Ball x2
Dive Ball x4
Max Elixir x4
Fighting Fury Belt x3
Acro Bike x4
Super Rod x2
Energy Switch x2
Stadiums - 4
Rough Seas x4
Energy - 12
Water Energy x12
The Manaphy is about $8-10, the Lapras/Glaceons are about $5-7 each. Octillery is like $2-3 last I checked, the rest of the cards should be under $1. Not sure how the UK's local card market looks by comparison but with the exchange rate you should be able to build this deck for less than 50 pounds.
The deck is designed around getting enough energy to attack on 2 Lapras GX then cycling between them with Manaphy's ability. Lapras's Collect attack can even help with draw consistency to some degree though attack based draw is vulnerable to N.
Glaceon is there as a way to deal with Lurantis and occasionally cheese easy wins against evolution only attacker decks. It can be subbed for Pyukumuku (and then work some bursting balloons into the list as well) as a cheaper but less effective stall option.