A Protestant is allowed to attend Mass. However, in most dioceses, intercommunion is not allowed. I suggest avoding intercommunion even in those dioceses that allow it because the Catholic Church regards communion as an expression of unity with herself.
The Latin rite Mass is entirely different from the Novus Ordo Missae. You would probably find yourself at a complete loss as to what was happening. Furthermore, they are often hard to find. There isn’t the slightest similarity between a Protestant service and the Latin rite Mass, but the beauty of this liturgy is very striking. The Traditional Latin Mass is also a very ancient liturgy. It was fixed for all time at the Council of Trent, but Tradition says that it goes back all the way to Saint Peter himself. The basic parts of the Latin Mass were in place by the second century. As a Traditionalist, I prefer to attend these masses, but rarely have an opportunity.
The Novus Ordo Missae would be much more familiar to you. In many ways, there are similarities between the English mass and a traditional Lutheran or Methodist communion service. The problems you would have are with some of the memorized prayers and with the standing, sitting, and kneeling. Most churches don’t have the order of Mass in their bulletins, so you have to follow a missal. It took me a few weeks to follow everything. If you have any questions let me know.