Internet Connections
There are a number of options when travelling and needing internet access, the simplest of course is to use a phone and setup a personal hotspot, then just connect to that. For more permanent solutions read on…
Basic
a 4G or 5G “Mobile Broadband”: These devices which are sold by all the networks offer a simple wifi experience for a few devices through a SIM card. The sim will be data only and you can shop around to get a reasonable deal. If you're travelling a lot and want to watch streaming TV services, then 'unlimited' is the only way to go.
With an External Antenna
There are a number of things to consider before fitting an external antenna;
4G or 5G - Many will claim to be universal but aren't and will give poor performance on 5G (or 4G if its a 5G antenna) Directional or Omni - Directional provides a far better signal, but you need to be able to point it so your installation will require some method of rotating it from inside the van, Omni of course doesn't need rotating but provides a poorer signal. Price - A good 4G/5G antenna won't cost you more than £150 at the very top end - remember anything 'motorhome' immediately means suppliers think they can change you 4x that.
Professional
If you MUST have internet because you're working on the road then there are a number of vendors who provide a pro solution.
Teltonika - well known and regarded with their range of 4G and 5G modems and routers. These devices provide more than just wifi some with dual SIM's so you can aggregate multiple networks as well as providing far superior performance. These aren't cheap though, but its a one off cost.