I've bought Amber from Gemporia, Gem Collector and Jewellery Maker in the past - and I've yet to find any with any notable inclusions. It's usually just bubbles of air.
I've got some STUNNING pieces of genuine Amber in the past from elsewhere that have contained inclusions of leaves, insects and / or bugs - and all for really good prices.
I go to quite a few Gem fairs now and you can find some really good gemstones of far higher quality, at better prices, with knowledgeable sellers that either mine themselves, or buy directly from source. Those sellers are, usually, PROPER geologists, minerologists or gemmologists that really know their stuff in depth. Not 'GIA accredited' people / presenters that only know the basics.
The Bakewell Rock Exchange is one of the best in the country.
There's also the Oxford Mineral Show.
There are the Rock, Gem and Bead Shows that travel around the country (
https://www.rockngem.co )
When it comes to buying online, I buy my loose gemstones from Gem Select (
https://www.gemselect.com ) and MultiColour Gems (
https://www.multicolour.com ) or AJS Gems (
https://www.ajsgem.com ) for rare, pricier stones (
https://www.multicolour.com ).
For fossils such as Amber or 'rough' specimens, etc, I buy them from the likes of Earthly Gems (
https://earthlygems.com ), Mineral Magpie (
https://www.mineralmagpie.co.uk ) and Stone Treasures (
https://www.fossils4sale.co.uk ) and direct from reputable miners or sellers that I've trusted for years, who I know are 100% genuine and only sell the real deal with paperwork to prove 100% authenticity.