The GP can order tests. I think the first test you should do is a sperm analysis. Another test is to check if your tubes are blocked. I can't remember the name of that one but they put some die into your uterus and look to see where it goes. It's a bit uncomfortable but worth it to know.

Your GP can order whatever tests you ask for but they might not know exactly what's available IYKWIM. If you are more comfortable with a specialist, then ask for a referral straight away. ETA: If you know of someone, you can ask for them, but otherwise, the GP should be able to recommend someone.

Good luck with this cycle. I hope you don't need any tests.