Saddlebag or panniers?

Hi

Touring newbie here, be kind!

In June I'm doing a 5-day trip from London UK to Lands End on a Cervelo Calendonia road bike. We're staying in hotels and hostels, so no camping gear.

Would you recommend a large saddlebag or small panniers (both combined with a handlebar bag) for the trip? For the latter, I'm thinking about the new Restrap thru axle rack or the Ortlieb equivalent.

Any other tips very welcome!

Thanks

Alan