Things to consider
You may be charged an initial installation fee and this will vary depending on the connection required.
You will need to pay monthly for possible ongoing line rental fees or data usage charges.
You will need to consider where to place your router as this can affect the over all coverage as signal strength will reduce the further away from the router you are. You may need to consider extending the Wi-Fi signal to reach other locations within the building. This can be achieved through powerline adapters or Wi Fi extenders but. This can come at an additional cost
Community buildings need a business contract - you should contact several ISPs to get the best deal that suits your community building.
Carefully consider and check the terms and conditions of your ISP as you will be making your internet connection available to the public. Check this with your ISP before placing an order.
There are alternative solutions that a community hall can explore if you require an immediate solution. You could explore getting connectivity via Mobile broadband (3G, 4G,5G), Fixed Wireless Access or Satellite.
You will need to be mindful of monthly costs and usage contracts when exploring an alternative solution.
There is a Welsh Government grant called the Access Broadband Cymru scheme that can fund (or part-fund) the installation cost of a new broadband connection for homes and businesses.
Community halls would have to be considered on a case by case basis