Grr, just had the computer seize up halfway through posting a reply.
The Historic England listing¹ has this to say about the hall: "Originally the Methodist Chapel, 1839. Stuccoed. Doric pilasters flanking the front. Cornice and parapet. 2 high windows with glazing bars intact. Projecting porch consisting of an Ionic column and pilaster on each side with pediment over, the porch being up a flight of wide steps. Large 6 panel moulded double doors. The interior contains a gallery supported on slender columns." and the photos afterwards mention Wesleyan Methodist. This latter makes sense, Wesleyan chapels tended to be larger and more ornate than Primitive Methodist chapels.
Kent Online² gives further history. After it ceased to be a chapel it became a music hall, then a Sea Cadet centre before finally becoming a party venue and being licensed for weddings. It lost its licence after complaints of anti-social behaviour including late night loud music, fights and parking problems. Kent Online includes pictures of its present state.
UKHallHire³ gives no additional information, but does include views of the interior before its present dilapidated state.
An interesting question is when it was first licensed for alcohol. Typically Methodist premises are sold on with a restrictive covenant banning the sale of alcohol. However total abstinence (as against temperance) developed in the latter half of 19C, so maybe the change to music hall predated this? Alternatively, was the putative covenant only lifted when it became a party venue? More history please!
¹
https://historicengland.org.uk/listing/the-list/list-entry/1318893?section=official-list-entry²
https://www.kentonline.co.uk/dover/news/inside-the-derelict-music-hall-abandoned-for-eight-years-291809/³
https://www.uk-hallhire.co.uk/halls/CT/20257.php