IT Support for Small Business on Occasional Basis

We are looking for someone who can provide occasional IT support to our staff when needed.
Our setup:
Draytek router with VPN
Synology NAS
10 PCs in the UK
4 remote workers
We need someone who can support us as and when IT problems arise, or to improve the IT / Office skills of our staff. Typical needs could be:
Troubleshooting VPN
Setting up new broadband on Draytek router
Fixing issues with our domains / DNS / CName
Liaising with programmers working on our inventory management system (you are not expected to be a programmer)
Providing desktop support to all staff
Improve staff skills on excel and other office applications
Look at ways of using IT to improve / automate our tasks.
We are a UK company, so we’d need support between 8.30am and 3pm UK time, Monday to Friday
Wage – $20 per hour
Hours – Will vary greatly. Some weeks there will be no work – other weeks there will be a few hours. As mentions, this will be on an 'as needed' basis.