I agree with Whammel. Putting your foot in a boot overnight sounds like it could be worse than doing nothing (also not a physiotherapist, but a long term user of various aids for foot-drop).
The best solution is indeed the FES. Most local CCGs (Clinical Commissioning Groups - they make the NHS rules for your local area) will fund FES, although some do not. My own CCG (Coastal West Sussex) does not routinely for MS, unless you are an ‘exceptional’ case. In fact it’s impossible to demonstrate you are exceptional. But ask your GP for a referral to Odstock Medical. They are based in Sussex but have outreach clinics all around the country.
Meanwhile, there are many products to help you walk with foot-drop. You can get a referral from your GP or neurologist to your local Orthotics department at the hospital. They can get you a foot brace, known as an Ankle Foot Orthosis (AFO) on the NHS. This keeps your foot in a suitable position for walking. But some of these can be awkward / uncomfortable. My local Orthotics department once ordered an AFO for me, then when I went for the appointment to fit the AFO, the technician realised it would not work. Apparently my foot/heel was the wrong shape!
Then there are more flexible devices such as Foot-Up® for Drop Foot - Drop Foot Support - Össur Webshop and https://www.orthotix.co.uk/shop/ankle-and-foot/boxia-drop-foot-afo/?gclid=EAIaIQobChMIz5zwkcyn4wIVxYbVCh1eIAdeEAQYASABEgL8RvD_BwE Both of these work on the same principle. A strap goes around your ankle, does up with Velcro and is attached to your shoe (or a shoeless wrap) by some form of elastic. They work alright, they’re not as good as FES, but are cheaper and easier to use. I often use one of these when I’m in a ‘legs won’t walk far’ kind of phase (which I am at the moment following a relapse).
The last type of device is a Silicon Ankle Foot Orthosis (SAFO). This is a custom made boot type thing that is made from a plaster cast of your foot. They cost quite a lot but some people swear by them (personally I find it’s virtually impossible to get shoes on over the foot with the SAFO on it!). The website is here: SAFO: Silicone Ankle Foot Orthosis | Dorset Orthopaedic
Whatever you try out, your physiotherapist will be very handy to help you out! (Or should be.) My physio has got me Foot-ups and a Boxia.
Best of luck.