moving in with a partner

If you move in together your Universal Credit claims will be linked and entitlement based on that couples claim.

https://www.gov.uk/government/publications/universal-credit-and-couples-an-introduction/universal-credit-further-information-for-couples

You can try using a benefits calculator:

https://www.gov.uk/benefits-calculators

Do remember it's cheaper for two people in terms of household running costs, compared to two people living apart and running individual households.