Cross is a very different animal from XC racing.
Races are 1 hr long but flat out the whole time, courses are short at around 6 mins a lap. Some races have a pit where you are allowed to change bikes, wheels and for mechanical assistance, some don’t in which case you can change wherever you like. Bottles are NOT allowed to be handed up, you can take one with you but none to be passed up during the race as it can cause accidents in the pits (this rule gets eased if it’s hot though sometimes)
Course is usually open for practice inbetween races and it’s usual/recommended to do at least one practice lap to get to grips with the course/find lines/set up equipment.
Cross is more like a road crit sometimes if it’s dry but it’s a great, cheap way into competetive bike racing, you can use any bike you like (other than in UCI ranked races) enter on the day (around £10) and it’s usually a very friendly atmosphere. check out the British cycling website for most of the info you need.