I walked it last Autumn the softy way, mainly staying in hotels and B&Bs. Book as early as you can as the WHW is hugely popular.
There are some stops where there is a very limited choice of accommodation:
Kingshouse - there is only the Kingshouse Hotel
Rowardennan - the Youth Hostel and the Rowardennan Hotel. The latter is pricey for what it is but they know that the only alternative is the YH. I plumped for the YH to save cash and it was truly dire - the room was a triangular cell with a broken radiator and a bed that would have violated the Geneva convention. The food was dreadful as well.
Don't rule out the option of having your luggage transported by van. It means that you only have to carry a daypack and this can make things much more enjoyable. The WHW is c95 miles long so, although your target of completion of 5 days looks reasonable in simple terms (i.e. less than 20 miles per day on average) it won't work out that way in reality. In fact, looking at this website, a 5-day intinerary might look like this:
Milngavie - Balmaha (20 miles)
Balmaha - Inverarnan (21 miles)
Inverarnan - Bridge of Orchy (19 miles)
Bridge of Orchy - Kingshouse (12 miles - easy day)
Kingshouse - Fort William (25 miles - tough day)
Most people seem to take 3 days to get to Inverarnan and, according to the landlady at my B&B there, that is the point at which people either give up or decide to get their bags transported as the previous day is a tough, up and down slog through forest with no views so don't worry if you get disheartened at that point.
However, the walk gets a heck of a lot better from there. In fact, if you're not the box-ticking type, start from Crianlarich. It's easy to get there from Glasgow by bus or train and Crianlarich - Fort William is easily the best part of the Way.