I take oral probiotics for the intimate flora everyday (optibac the purple ones) as well as inserting vaginal probiotics ovules (the ones from canesten canesflore) on the days when I'm not working.
About 3 times a week at night, I insert lactic acid gel into the vagina (canesten canesbalance) to help maintaining a good ph to prevent BV, lactic acid helps stimulate the growth of lactobacillus which are the bacteria that are naturally present in your vagina and keep it healthy (probiotics contain lactobacillus). Lactic acid also helps a lot at getting rid of a bad smell if you get BV.
Probiotics + lactic acid really helps prevent thrush and BV.
(All those products can be found at Boots)
On the other side, if I ever get a thrush (which is rare thanks to probiotics and lactic acid), I insert a vaginal pessary from canesten and apply the external cream clotrimazole. If you want an extra layer of defence to clear the thrush asap, I also take one pill of oral fluconazole on top of the cream and vaginal pessary. (products also found at Boots)
In case of BV, you need to take 2 tablets of oral metronidazole (prescribed by a doctor) for 5 days, alternatively, you can get the Zidoval gel which is metronidazole in the gel form to insert into the vagina at night depending what you prefer using.
I would also strongly advice against any "vaginal showers" whatsoever or inserting any water or any liquid that is not specifically made for that area as those vaginal showers can really damage the vaginal flora and cause BV and thrush.