Eyy! Chilworth are part of the Subiaco-Cassinese congregation, the same as Farnborough Abbey, where I spend more time than is healthy! They are good lads, they follow the Rule and they’ll take good care of you.
Are you discerning for a diocese? I was an A&B seminarian until January.
Also, Chilworth Abbey is the home of the benedictines (as they are run by an Abbot). Chilworth Friary is where the Franciscans live, as they are friars.
No particular dress code - bring tough clothes for manual labour, wellies, waterproofs, and smart-ish clothes for the rest of the time (especially for Holy Mass!). Consider brining a suit for Sundays.
If you’ve been accepted for a diocese by the time you get there (which means you can call yourself a seminarian), you might be able to persuade the Abbot that wearing a cassock is entirely proper!