Is it the upright sitting position that you like about dutch bikes or is it the traditional styling, ie the facility to add shopping baskets etc?
Most bikes in the UK are road racing bikes or mountain bikes, both of which lean you forward. Racing bikes especially, for aerodynamic reasons. On the continent however, drop handlebars are few and far between. There are a lot of mountain bikes but mostly these tend to lack all the drilled holes in the frame for mudguards, panniers, lights etc. The city or touring bikes have them and many more extras. You'll hardly find one without a bike stand for example.
The extra tough touring bikes like those from Koga are expensive and models like their World Traveller come with mobile phone chargers built in. But these bikes are for people who will be cycling where there are no hotels. At my age, I have no intention of that sort of touring so I settled on a more reasonably priced model, an S'cape HB7 from
Decathlon in Belgium:
I got that for a very good price, £500, which considering it has Deore XT gears is a bargain. It has butterfly handlbars but it would be easy to add those dutch ape hanger type bars that you see at dutch bike bits. All the same, this bike will take all the traditional baskets if that what you are after, like this one which clips onto the rear pannier bracket:
If it is an upright touring style that you like, an abolsute bargain is the
Radon with Rohloff gears from
www.bike-discount.de whereas if it is the tradtional look that you are after, they tend to come in 'old fashioned'
http://www.dutchie.co.uk/dutch-bikes/
and modern with traditional look:
http://www.dutchbike.co.uk
Royal Dutch Gazelle make a range which can be purchased in the UK but if you scour the internet or if you are prepared to go as a foot passenger on the ferry and buy one on the continent, you will have a wide range and probably get one cheaper.
http://www.decathlon.be/C-409900-velo-de-ville