Newbie needs advice on spray varnishing?

Hi folks,

I've just completed my first ever build-a 1/48 Tamiya Tiger I. Bearing in mind it's my first EVER model it's turned out far better than I could ever have possibly imagined!

I did my homework, read books and magazines and joined this forum long before I started the build-it really paid off!

I put some pictures in the Armour section yesterday of my tank nearly finished, please take a look and tel me what you think-all that was to done was some dry-brushing and weathering.

My final question is this; The chap in my local hobbyshop who has been very helpful throughout my first build gave me a tin of 'Humbrol Model & Craft Hobby Spray Varnish for Enamel Paints', suitable for plastic kits etc......on the lid it is called 'Enamel matt varnish'.

He said that once my kit was TOTALLY complete, paint and weathering, everything, to take it outside, put it on some newspaper and get the spray varnish out. He said to shake it very well-he said a timed 3 minutes-and with light strokes apply the spray.

I'm fine with this but should I be doing it? I understand it will seal the kit nicely and keep my weathering dust in place etc but I really don't want to take to my perfect tank (imo) and ruin it with this spray!!!

Can anyone give me advice on how best to apply this or even tell me wether I SHOULD be applying it at all?

For the record, the tank has been painted with Humbrol enamel paints and dry brushed with Humbrol white paint. For mud effect, again I've used various brown paints and have given it a light dusting with Tamiya weathering powder.  

Many thanks,

Ben