Yes, you can.  HMRC rules state that the majority of the use of the bike must be for commuting and this can be over the lifetime of the bike.  So whilst you may not use it much for commuting at the moment, you will more than make up for that over the coming years.  You may also want to take time to build your fitness levels in preparation for your new commute to work.  By working at home you are probably saving money by not indulging in daily coffees or buying train tickets.  So it makes sense to get a new bike now so you are prepared for when your place of work does reopen and life returns to some sort of normality.