In general, yes, but check the walk description.
All of the walks on our programme are open to the general public, but some may require you to sign up in advance (e.g. linear walks where the organiser is arranging transport and needs to know how many people are going).
You should be confident that you are fit enough to complete the walk - if in doubt, start with an easier walk and work up to the more difficult ones.
You should also ensure that you wear appropriate clothing and bring appropriate equipment.
If you have any questions, feel free to contact the walk leader - their contact details should be available on the walk description.