I think it depends a bit on your circumstances. When both my Cavaliers were terminally last year, I claimed for everything except actual vet visits - medication, prescriptions, visits to specialists. Aled was on expensive MVD medication, and that and the intensive care and full cardiologist examination when he went into heart failure in July added up but the insurance did pay out. When his insurance was to be renewed in January, the premium shot up to £180 a month, and as that was more than his medication, and he clearly wasn't going to live much longer, I didn't renew. The insurer (Axa, who no longer do pet insurance) was very good about paying for regular medication and prescriptions - they just took off the excess once a year and then paid every claim in full.
It might be worth looking around for a cheaper insurer who will accept a 10 year old, or starting to claim on your present insurance if Bailey isn't likely to need very expensive treatment in the foreseeable future. Or you could do what some people do, which is stop the insurance and put £86 a month into a special bank account. Talk to your current insurers about whether, if you claim for regular medication (and prescriptions), they will only take off the excess once a year - £100 a month is only £1200 a year, so if your cover is for £4000 or £7000 there will still be plenty for emergencies. When your premium exceeds what you would be paying for medication, you may need to have another think.
Sorry, probably not very helpful - but it seems a bit wonky to be paying for both your premium and Bailey's medication. If you're paying out £186 a month anyway, it might be worth claiming, to save yourself £100 a month, and you would still have a bit of leeway on a raised premium if you weren't paying out the £100 a month.
Kate and Ruby