Swimming Club

Does anyone know of a swimming club or team that accepts swimmers looking to improve performance? I swim several thousand metres per week but my technique could be much better and my training would be vastly improved if it was done as part of a team with some skilled guidance. I'm not looking for top-flight competition as I am not terribly quick. I'm in my mid-30s so believe I am looking for Masters level or equivalent. Ideally located in the eastern half of Brussels - must be on public transport. Many thanks.