Although there may currently be COVID-19 restrictions limiting attendance at church services, normally, everyone is welcome to attend a Catholic church service (Mass). However, only Catholics “in a state of grace,” i.e., only Catholics who have no unconfessed serious sins, are suppose to receive Holy Communion, i.e., eat the bread or drink the cup of the Lord.
I recommend attending Mass with a parent or trusted adult and a Catholic friend, so they can help guide you through the service.
Because, as others have mentioned, a Catholic church service (Mass) is quite different from a Baptist church service, it would probably be a good idea to familiarize yourself beforehand with the order of service of a typical Catholic Mass and with what you would be expected to do and say, if you wanted to participate along with the rest of the people in the congregation.
Since you indicated you are Scottish, here’s a link to a PDF produced by the Bishop’s Conference of Scotland of
The Order Of Mass that might be helpful. It indicates when and what the people are to do, such as stand, bow, sit, kneel, make the sign of the cross, strike their breast, or offer a handshake to those nearby, and what they are to say in response to the things the priest, deacon, and other ministers say.