No need to enter, just buy what you think works and give it a go at home. Here's the returns policy
If you’re not totally satisfied with your IKEA purchase you can return
your products within 365 days, even if you assembled them, as long as
they’re in an unused. Please return them with proof of purchase
(original receipt) and, if possible, the packaging.
I haven't returned anything to Ikea for about 20 years. That was due to finish quality issues and the return was a massive hassle because there were huge queues. I've found quality control has improved, has customer service?
I've returned a few things in the last few years. We did our kitchen up and had heaps of leftovers. Returned about 30 packages, took maybe 10 minutes. This was in Sweden though, but can't see UK being that much different.
Last time I went to Ikea the queue for returns was massive and slow moving. It was a couple of days before the second lockdown which may have made it worse.
No need to enter, just buy what you think works and give it a go at home. Here's the returns policy
https://www.ikea.com/gb/en/customer-service/returns-claims/return-policy/