Hi Jamie, welcome to HERAS.
There is a general rule about magnification - the maximum useable magnification is about 50x for each inch of aperture. Thus, for your 4.5 inch scope you would be looking at a max of about 225x.
You calculate the magnification as: telescope focal length divided by eyepiece focal length, which means that the 3.5 mm eyepiece giving about 160x mag should be OK.
For your 'scope you have: min magnification 16x (35mm eyepiece), max perception of detail at 57x (10mm eyepiece) and max magnification 225x (2.5mm eyepiece).
Your 'scope being f/5, should provide excellent views of the brighter deep sky objects. Try M13, M31, M27, M57, M82. Find them using your 25mm, then use the 10mm for seeing detail.
As regards viewing, you may want to have a look at the BLAS site. BLAS are based at Brough and have their own dome.
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