UK-based mixture supplier
Only EU/EEA-based importers and downstream users can submit a notification under Article 45 (poison centre notifications). Furthermore, the obligations have to be fulfilled by each duty holder individually. If your company is based in the UK and has notified a mixture to the relevant appointed body in the Member States where your EU-based distributors place it on the market, this asset cannot be transferred. The information submitted remains in the database and is available to the appointed body once they get access to the harmonised submissions.
Nevertheless, the EU company will need to submit a notification themselves if they intend to import the same mixture into the EU. The EU company cannot rely on the notification made by the UK supplier.
Note that a UFI code generated with a UK VAT can still be used by EU companies. The reason being that the ultimate role of this code is only to link the product on the market to the submitted information.
In general, if you want to export mixtures to the EU, your products will have to comply with the EU regulations, including the CLP Regulation. This means that you, together with your EU-based importer, will need to classify and label your products in accordance with CLP.