Netgear Mobile Router MR5200 (Sim Card question)

Good afternoon

I have recently purchased the above mobile router. I have been advised that all sims will be ok but must be activated with a data subscription for an operator.

This will be used solely when we go abroad or camping. 

Can i just purchase a sim with data only on and with the possiblity of pay as you go. If pay as you go is possible how do i get more data added by the operator with the sim card in. 

Look forward to hearing from anybody who can help me as I am not very good at technology.

Regards

Jupiler