If you play to a high standard*, and can commit to weekly rehearsals and concerts, as well as to practice, come along and join in.
There are no auditions, simply turn up in good time to the Wednesday weekly rehearsals at the beginning of either the Autumn or Spring programme (ie beginning of the autumn season, or after the November concert), introduce yourself to the conductor and leader, and start making music. The section leader and librarian will help you find the sheet music and a place to sit.
You may attend a couple of rehearsals for free before committing to join, just to make sure that you are comfortable with the standard. If you decide to join, there is an annual subscription, which is like to be around £80 for standard membership, and £20 (£10 per term) for students or those from unwaged households. The exact subscription for the forthcoming season will be decided for each year at the AGM on September 2023.
*Sometimes new members like an approximate ABRSM grade as a guide; this should be at least Grade 6-8; but we are aware that some adult learners may never have taken any actual exam, yet still play to at least this standard, while others may hold the certificate from years ago, but have "lapsed". The easiest thing is to try out the orchestra for a few weeks.