See the flat. Pick what works for you.

Same flat as quad but with one fewer flatmate. We'll keep one bed empty for you.

Quietest sharing option. You'll share the flat with only one other person.

Take two beds in the same flat — could be both in the bedroom (private together) or split.

You pay for both beds in the bedroom but use just one. Nobody enters your room.

Pay for the whole flat. Use it however you like — guest bedroom, home office, the works.